Field of the Invention
The present invention relates to a wireless communication, more specifically an operation method for calling performed by the terminal and the terminal using the method.
Related Art
In an International Telecommunication Union Radio communication sector (ITU-R), a standardization of International Mobile Telecommunication (IMT)-Advanced being a next mobile communication system after a third generation has been performed. The IMT-Advanced is aimed at supporting an Internet Protocol (IP) based multi-media service with a data transmission rate of 1 Gbps in a stop and low speed moving state and a data transmission rate of 1 Gbps in a high speed moving state.
A 3rd Generation Partnership Project (3GPP) is preparing LTE-Advanced (LTE-A) being an improved one of Long Term Evolution (LTE) based on an OFDMA (Orthogonal Frequency Division Multiple Access)/SC-FDMA (Single Carrier-Frequency Division Multiple Access) transmission scheme as a system standard satisfying requirements of IMT-Advanced. The LTE-A is one important candidate for IMT-Advanced.
In recent years, there is growing interest in a Device-to-Device (D2D) technology performing direct communication between devices. In particular, the D2D is attracting attention as a communication technology for a public safety network. A commercial communication network has been rapidly changed to the LTE but a current public safety network is based on a 2G technology in a collision problem and a cost side with an existing communication standard. Request for the technology clearance and an improved service induces an effort to improve the public safety network.
Meanwhile, a terminal communicates with a base station after establishing a RRC (radio resource control) connection with the base station. When the terminal establishes the RRC connection with the base station, it provides the network with information indicating cause or reason establishing the RRC connection.
In a prior art, since any call for the purpose of public safety does not exist, a value capable of identifying the call for the purpose of public safety has not been yet provided for the information indicating the RRC connection establishment cause.
Thus, an appropriate access control is required to be provided by effectively identifying between the call for the public safety and other call.